feat(api): add terminal session persistence with Prisma model and CRUD (#517)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/api/src/terminal/terminal-session.service.ts

@@ -0,0 +1,96 @@
+/**
+ * TerminalSessionService
+ *
+ * Manages database persistence for terminal sessions.
+ * Provides CRUD operations on the TerminalSession model,
+ * enabling session tracking, recovery, and workspace-level listing.
+ *
+ * Session lifecycle:
+ * - create: record a new terminal session with ACTIVE status
+ * - findByWorkspace: return all ACTIVE sessions for a workspace
+ * - close: mark a session as CLOSED, set closedAt timestamp
+ * - findById: retrieve a single session by ID
+ */
+
+import { Injectable, NotFoundException, Logger } from "@nestjs/common";
+import { TerminalSessionStatus } from "@prisma/client";
+import type { TerminalSession } from "@prisma/client";
+import { PrismaService } from "../prisma/prisma.service";
+
+@Injectable()
+export class TerminalSessionService {
+  private readonly logger = new Logger(TerminalSessionService.name);
+
+  constructor(private readonly prisma: PrismaService) {}
+
+  /**
+   * Create a new terminal session record in the database.
+   *
+   * @param workspaceId - The workspace this session belongs to
+   * @param name - Optional display name for the session (defaults to "Terminal")
+   * @returns The created TerminalSession record
+   */
+  async create(workspaceId: string, name?: string): Promise<TerminalSession> {
+    this.logger.log(
+      `Creating terminal session for workspace ${workspaceId}${name !== undefined ? ` (name: ${name})` : ""}`
+    );
+
+    const data: { workspaceId: string; name?: string } = { workspaceId };
+    if (name !== undefined) {
+      data.name = name;
+    }
+
+    return this.prisma.terminalSession.create({ data });
+  }
+
+  /**
+   * Find all ACTIVE terminal sessions for a workspace.
+   *
+   * @param workspaceId - The workspace to query
+   * @returns Array of active TerminalSession records, ordered by creation time (newest first)
+   */
+  async findByWorkspace(workspaceId: string): Promise<TerminalSession[]> {
+    return this.prisma.terminalSession.findMany({
+      where: {
+        workspaceId,
+        status: TerminalSessionStatus.ACTIVE,
+      },
+      orderBy: { createdAt: "desc" },
+    });
+  }
+
+  /**
+   * Close a terminal session by setting its status to CLOSED and recording closedAt.
+   *
+   * @param id - The session ID to close
+   * @returns The updated TerminalSession record
+   * @throws NotFoundException if the session does not exist
+   */
+  async close(id: string): Promise<TerminalSession> {
+    const existing = await this.prisma.terminalSession.findUnique({ where: { id } });
+
+    if (!existing) {
+      throw new NotFoundException(`Terminal session ${id} not found`);
+    }
+
+    this.logger.log(`Closing terminal session ${id} (workspace: ${existing.workspaceId})`);
+
+    return this.prisma.terminalSession.update({
+      where: { id },
+      data: {
+        status: TerminalSessionStatus.CLOSED,
+        closedAt: new Date(),
+      },
+    });
+  }
+
+  /**
+   * Find a terminal session by ID.
+   *
+   * @param id - The session ID to retrieve
+   * @returns The TerminalSession record, or null if not found
+   */
+  async findById(id: string): Promise<TerminalSession | null> {
+    return this.prisma.terminalSession.findUnique({ where: { id } });
+  }
+}